Yesterday, a Tweet appeared in my feed, directing me to a Sparkfun blog post describing how to use popsicle sticks and paper clips to make a 2.4 GHz WiFi Yagi antenna. I love this project so much that I thought I’d give it some publicity here.
As you can see, it’s really more than a Yagi antenna, though. It’s more like a 2.4 GHz field strength meter. The board on the antenna beam is a SparkFun ESP8266 Thing, which includes an Arduino-compatible microcontroller and a WiFi interface. The microcontroller is running a sketch (that’s what the Arduino folks call a program) that reads the received signal strength from the WiFi chip on the board and displays that value on the little LED display.
Using some antenna simulation software, the author calculated a gain of 10 dBi for his little Yagi, and in practice, it yielded a gain of about 6 dB over the onboard PCB antenna. That’s pretty good considering that the PCB antenna probably had some amount of gain and there was probably some loss in the cable. And, as the author pointed out, he made no attempt to match the antenna’s impedance.
One improvement I’d suggest using a dowel or maybe a square stick of wood instead of the popsicle sticks. While using popsicle sticks is cute, I’m not sure how sturdy that boom really is.
Finally, I love the author’s suggestion of using this device for fox hunting. These devices would be inexpensive to make, and I think they would work very nicely, at least in an area that didn’t already have a lot of 2.4 GHz WiFi signals.
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